To whoever face this issue in the future, in our case it was caused by a plugin called 'vite-vercel-plugin' which configs how Vite projects integrate with Vercel's Serverless functions and one of the things it does is to manually generate an '.vercel/outputs' folder, which was causing the conflict with the one generated automatically by Vercel, in addition of that, we've noticed that this plugin started updating their dependencies about 2/3 weeks ago, which is around the time we started facing these issues, although it might be just coincidence, we've solved our issue by removing this plugin from our project.